I. Field of the Invention
This invention relates to a gasket to seal a joint connecting two sections of an exhaust system for a vehicle and, in particular, to a gasket which incorporates means for improving the sealing capabilities along the joint as well as structure for seating the gasket retarding rotational and axial movement of the gasket within the joint.
II. Description of the Prior Art
Government regulations have increasingly limited the permissible levels of leakage within an exhaust system of a vehicle. By minimizing exhaust leakage and thereby maximizing the flow of exhaust through the system, pollution control devices are provided every opportunity to eliminate harmful pollutants. Furthermore, exhaust leakage beneath the vehicle can be harmful to the vehicle occupants and therefore the system should maximize the flow of exhaust to the rear of the vehicle. The exhaust system is also designed to muffle noise from the engine resulting from combustion and any leaks would allow this noise to escape.
The gaskets or seals used in exhaust systems are provided in a variety of configurations, but are subject to extreme levels of heat and pressure which can result in their deterioration and failure. The most common is the flat gasket which is dependent upon the clamping force of the system flanges. As heat and pressure vary, expansion and contraction of the joint allows leakage. Various alternatives have been utilized including bi-metallic seals designed to expand differently to ensure that at least one component is sealing the joint. Compression beads and ancillary flanges may also be used to accommodate expansion of the exhaust joint to prevent leakage between components.
Of concern in the assembly of exhaust systems is improper seating of the gasket seal. Flat gaskets must be carefully positioned to ensure proper sealing. Even gaskets which partially mate with a component can rotate out of alignment compromising the sealing ability of the gasket. Despite all of these requirements, the gasket must remain a relatively inexpensive component of the exhaust system and therefore simple to manufacture.